Novel hydrophilic membrane materials: sulfonated polyethersulfone Cardo

Sulfonated polyethersulfone Cardo was prepared by solvent-free reaction of concentrated sulfuric acid on the polymer. The polymer can be sulfonated to different degrees by control of the reaction temperature and time. The degradation of it main chain was shown to occur at high reaction temperature or at very long time. Higher sulfonation obtained at longer reaction times led to soluble polyelectrolytes. Polymers with an ion exchange capacity lower than 1.75 equiv. kg−1 are not soluble in water while being hydrophilic. Asymmetric membranes can be prepared from the latter polymers by the wet phase-inversion method with water as the precipitation medium. They can be used as hydrophilic membranes for ultrafiltration or nanofiltration.